Wrap-around simulation systems are often used to simulate flying and driving through various scenarios and scenes. These simulators are especially popular for training pilots to fly aircraft. In these systems, an out-the-window scene is generated and displayed to the user. The image is generated as pixels and projected on one or more projection screens representing a user's filed of view. Since the projected out-the-window scene is usually large, it will often be at a low pixel per area unit, resulting in low resolution imagery.
Commercial off the shelf high-resolution projectors have become available in recent years that are capable of projecting high resolution video onto large screens. These projectors are already replacing some of the projectors used in movie theaters. These HDTV projectors display images that have what is generally described as a 16:9 projection aspect ratio, meaning the width to height ratio of the image. In some displays, the actual ratio of width to height in the display may vary, although the aspect is usually a wide-rectangular image much greater than the previous standard of 4:3.
It would be desirable to display a simulation scene in high resolution so as to present a more realistic experience for a user, and so as to allow the user to see and distinguish both faraway objects and targets such as those that would be seen by pilots in the real world, as well as the terrain or background comprising the out-the-window (“OTW”) scene, at or near eye-limiting or 20/20 resolution, meaning the degree of resolution that corresponds to the visual acuity of the average human eye.
Prior art systems have provided high-resolution imagery in very limited portions in the field of view for viewing individual targets, by providing a separate target projector that can place a small high-resolution field in selected locations on the screen, such as the target projector shown in U.S. Pat. No. 6,552,699 B2 to Dugdale, which is incorporated herein by reference. Unfortunately, the high-resolution area of the target imagery is only in the very small area of the target aircraft being displayed. The rest of the OTW scene is a low-resolution image.
High definition television projectors available on the market now can achieve the necessary high resolution, but existing screen systems are not configured to work efficiently with current commercial off-the-shelf (COTS) HDTV projectors. Prior-art wrap-around rear projection simulation systems are typically constructed from screens that are joined so as to form partially-closed dodecahedral and truncated-icosahedral (a polyhedron having 12 regular pentagonal faces and 20 regular hexagonal faces, 60 vertices and 90 edges) shaped structures. FIG. 1 shows the classical dodecahedron shape, and FIG. 2 shows the truncated icosahedron shape of simulator displays of the prior art, which use a combination of pentagonal or hexagonal faces having an approximately 1:1 aspect ratio.
In these prior art systems, such as seen in, e.g., U.S. Pat. No. 5,602,978 to Lastinger and U.S. Pat. No. 5,023,725 to McCutchen, both herein incorporated by reference, one or more video projectors are mounted outside the screen structure of interconnected polygonal screen panels, each having approximate 1:1 aspect ratios. Each video projector projects sequential images of video on a respective outer or rear face of a respective screen panel so that the images can be viewed from the front face of the screen panel inside the screen structure.
Unfortunately, because high resolution projectors normally project video images at aspect ratios significantly higher than past projectors, they cannot be efficiently used in screen arrangements of the prior art, which are made-up of screens having approximately 1:1 aspect ratios. This difficulty is illustrated in FIG. 3, which shows a 16:9 high-definition projection 200 mapped onto a pentagonal screen 202 having a 1.05:1.00 aspect ratio. The shaded area 204 represents lost or wasted projected pixels of the high-definition projector's field of view that are not applied to the screen 202.
To efficiently employ each high-resolution projector's full field of view with a prior-art projection screen system, multiple high-resolution projectors could be used on each screen of the screen structure. Unfortunately, using multiple projectors per screen are represents a prohibitive additional cost for the additional projectors, as well as additional labor resulting from having to matrix these projectors so as to display the appropriate portion of the out-the-window scene. Also, it is difficult to minimize the gaps between the separate projected videos so as to ensure a seamless projection of two videos from two sources on a single screen panel.